1. Field of the Invention
The invention concerns control of odor arising from the presence of hydroxypropyl trialkylammonium salts in personal care compositions.
2. The Related Art
Hydroxypropyl trialkylammonium salts have a number of beneficial cosmetic properties. Foremost is the ability of these salts to moisturize skin. The moisturization benefits have been revealed in U.S. Pat. No. 7,087,560 B2 (McManus et al.), EP 1 807 041 B1 (Unilever), EP 1 804 922 B1 (Unilever) and U.S. Pat. No. 7,282,471 B2 (Harichian et al.).
Another benefit of these salts is that they can mediate the signs of aging. This benefit is reported in U.S. Pat. No. 7,176,172 B2 (Harding et al.).
In developing dihydroxypropyl trialkylammonium salt containing personal care compositions, there has been noted a malodor problem. Off-odors have been attributed to small amounts of low molecular weight trialkylamine continuously being generated from the salt compositions. Even small amounts of amine are readily detected by the human nose.
U.S. Patent Application Publication 2007/0299284 A1 (Deavenport et al.) discloses attempts to inhibit malodors from dihydroxypropyl trialkylammonium salts. Their solution is to reduce the pH of the intermediate reaction leading to the final quaternary ammonium salts. No guidance is provided on controlling odor of personal care compositions that may contain the salts.
Accordingly, the present invention is focused upon reducing malodour arising from volatile trialkylamine which is generated by dihydroxypropyl trialkylammonium salts in a formulated personal care composition.